TW201226065A - Method and device for the depollution of a pelliculated reticle - Google Patents

Abstract

The object of the present invention is a device for depolluting a non-sealed, confined environment (1) having a natural leakage (6) and including an interior space (9) bounded by a wall (7), comprising a depollution enclosure (11, 30) means (32, 42) for pumping gas and means (33, 43) for introducing gas. The depollution enclosure (11, 30) has at least two chambers (12, 13; 31, 41) separated by a sealing wall (14, 49). A first chamber (12, 31) is constituted by the part of the enclosure that is situated in contact with the wall (7) of the non-sealed, confined environment (1) and cooperates with first means for pumping (42) and first means for introducing gas (43), and a second chamber (13, 41) is constituted by the part of the enclosure which is situated in contact with the natural leakage (6) from the non-sealed, confined environment (1) and cooperates with second means for pumping (42) and second means for introducing gas (43). The first and second means for pumping gas (32) and (42) have a pumping capacity which can vary independently, and the first and second means for introducing gas (33) and (43) having a gas injection flow rate which can vary independently. The device for depolluting also has means to control the difference in pressure between the interior space (9) and the first chamber (12, 31).

Description

201226065 VI. INSTRUCTIONS OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for eliminating molecular contamination under a film of a reticle or mask and to an apparatus for performing the method. [Prior Art] A photomask is equivalent to a negative film in photography: its effective surface contains a piece of information to be printed on a carrier. It is used for the transmittance of exposure and printed on a semiconductor substrate. The incident beam is focused on the active surface of the reticle and the pattern contained in the active surface is then replicated on the substrate. The contamination of the reticle has a direct effect on the image printed on the substrate, with defective printing. The semiconductor industry is seeking to reduce the size of recorded images to obtain increasingly smaller, integrated and low cost electronic components. When the size of the reticle becomes smaller, the requirements for pollution become more stringent. Photomasks are therefore an extremely important, expensive and complex component that is sought to remain clean and functional. At the end of its manufacture, the reticle is cleaned and inspected. If the reticle is clean and flawless, a film is applied to it to protect its effective surface. Contaminants that are likely to become deposited on the active surface of the reticle will thus become deposited on the film. The film is thus intended to protect the reticle for the user throughout its useful life. The film is comprised of an optical film (including parallel multilayer surfaces) that has high transmission and limited impact on the beam passing through the film. The film is most commonly joined to the edge of the active surface of the reticle and separated from the reticle by a space

-5- 201226065. The atmosphere below the film is then isolated from the atmosphere used. To prevent the film from becoming deformed, the holes of the device are designed on the side of the film. This leaking role' balance is limited to the large pressure below the film. It has been felt that the intensive use of contaminants can still cause the inverse of the gas existing between the substrate and the film on the effective surface of the reticle, especially the ammonium sulfate crystal (NH4) 2 focusing. In the region, the effective surface of the reticle and the phenomenon of the size reduction in the technique are directly reduced (printing with defects). Its location below the film results in a cleaning of the reticle that is difficult to clear. A lengthy, complicated and expensive film usually needs to be removed for cleaning and then reworked must be done by the reticle manufacturer and not by such Loss of use and management of the extra-light costs associated with shortening the service life. Therefore, it is obliged to have no molecular pollution for the environment under the dense shadow mask. In order to ensure the effectiveness of the reticle to prevent molecular contamination of the membrane, a method has been proposed which includes an internal atmosphere for pumping out, a restricted environment and then resuming operation of the restricted environment to prevent extreme forms of contamination. Any operation. The gases are transported through the housing of the reticle to have low conductivity filtering of the holes to create a natural gas and the atmosphere outside the film. Photomask defect. These sources of defects should be. For example, the growth of crystals into S〇4 can be between the films. These are affected by the lithography steps. It has been set up with its thin process because of the thin placement. The finer operator performs, causing the user of the time cover to determine the film without removing the film. Or discharging the unsealed atmospheric pressure without hitting may cause a particularly natural leak. • 6 -

S 201226065 Passing to the outside and vice versa in an unsealed environment. In the case of a reticle, the passage of the gas is made by a hole having a low conductivity filter provided on the side of the film. However, it is then necessary to provide a mechanism to prevent any deterioration of the wall of the unsealed, restricted environment because these walls are not able to withstand significant differential pressure without deterioration. In the case of the reticle, the film is damaged once the stress applied thereto causes deformation beyond its elastic limit. This limitation depends on the type of film, and the films of the masks are not identical. The film typically fails to withstand differential pressures greater than about IPa because the film does not deform more than two millimeters without damage from the viewpoint of concavity or crown. To prevent this damage, the drop in pressure can be adjusted so that the difference in pressure between the inside and the outside of the unsealed, restricted environment is less than any difference in the pressure that will cause mechanical deformation, which is damaged. The risk of this wall. For reticle, in these conditions, a drop in pressure from 1 000 mbar to 10 mbar, followed by an increase in atmospheric pressure takes more than five hours. It can be understood that it is not possible to significantly accelerate this method without damaging the mask. However, this period is far longer than the industrial needs. In fact, the time spent troubleshooting should not exceed 30 minutes, especially in factories that manufacture electronic wafers. SUMMARY OF THE INVENTION The present invention is also directed to an unsealed, restricted environment for a period of time shorter than that obtained by prior art methods, that is, a period that will be short enough to be compatible with production constraints. 201226065 Apparatus and method for efficiently preventing molecular contamination. The present invention is also directed to apparatus and methods for preventing molecular contamination in an unsealed, restricted environment without the need for the environment to be opened and to not damage walls having low impedance to pressure differences. Yet another object of the present invention is to provide an apparatus and method for effectively eliminating contaminant compounds that can be positioned between the active surface and the film of the reticle without removing the film and the need One is smaller than the previous technique. The object of the present invention is a device for preventing unsealed, restricted environmental pollution, the environment having a natural leak and an internal space defined by a wall, the device comprising: - a pollution prevention enclosure, capable of containing An unsealed, restricted environment, a mechanism for pumping gas out of the pollution prevention enclosure, and a mechanism for introducing gas into the pollution prevention enclosure. The pollution prevention enclosure has at least two chambers separated by a sealing and separating wall surfaces, the wall surface being able to withstand the difference in pressure between the two chambers: - the first chamber is located unsealed by the sealing member, Consisting of wall contact of a restricted environment and cooperating with a first mechanism for pumping gas and a first mechanism for introducing a gas, the second chamber being located and unsealed by the seal member a natural leaking contact in a restricted environment, and a part of the second mechanism for pumping gas and a second mechanism for introducing gas, which constitutes the first and second mechanisms for pumping gas, It has a pumping capability capable of independently varying and a first and second mechanism for introducing a gas having a gas injection flow rate that can be independently varied, and means for preventing contamination includes controlling the unsealed A mechanism for the difference between the pressure in the internal space of the restricted environment and the pressure in the first chamber. To significantly accelerate the prevention of molecular contamination in an unsealed, restricted environment, the pressure must be maintained within the interior of the unsealed, restricted environment such that throughout the first chamber, the contamination prevention operation It is as close as possible to the popularity of the outside. By means of the device and the associated method, it may depend on the pressure to be achieved and the optimization of the method, reaching a few minutes (for example, 1 to 30 minutes) to several hours (for example, 1 to 5 hours). Prevent pollution time. Advantageously, the first chamber has a smaller volume than the second chamber. In practice, the volume of the first chamber must maintain a pressure that is as close as possible to the pressure in the interior of the unsealed, confined environment to prevent deformation of the wall. In order to improve the reactivity in the adjustment of the pressure, the volume of the first chamber must be as small as possible. According to a first embodiment of the invention, the first chamber is transparent to light. According to a preferred aspect, the apparatus has means for measuring the deformation of the wall of the unsealed, stressed environment. The mechanism for measuring the deformation of the wall includes a laser that emits a beam of light toward a wall of the unsealed, restricted environment, and a light receiver that receives a beam of light reflected by the wall of the unsealed, restricted environment .

-9- 201226065 According to a special implementation form 'a mechanism for controlling the difference between the pressure in the internal space of the unsealed, restricted environment and the pressure in the first chamber' is used to measure the unsealed, A mechanism for deformation of the wall of a restricted environment. According to another embodiment, the apparatus further includes means for activating to independently modify the rate of pumping in each of the chambers. In order to obtain a variation in the pumping capacity of the pumping mechanism, it may be, for example, the speed of the motor that controls the pump unit and/or the opening of the variable conductance valve. According to yet another embodiment, the apparatus further includes a mechanism for activating to independently modify the flow rate of the gas injected into each of the chambers. In order to obtain a change in the flow rate of the gas injected into the pollution-preventing enclosure, it may be possible to control the incoming gas flow by means of a mass flow meter and/or by opening a variable conductance valve. Still another object of the present invention is a method for preventing contamination of an unsealed restricted environment by means of the previously described apparatus, the environment having natural leakage and including an internal space bounded by a wall, the method comprising the following steps - placing the unsealed, restricted environment in a pollution-preventing enclosure comprising two chambers separated by a seal, separating the walls » setting up a separate wall seal in the unsealed, restricted environment - by independently adjusting the pressure drop in each of the chambers while sequestering the gas contained in the first chamber and the gas contained in the second chamber - 201226065 The pressure in the unsealed, confined interior space and the pressure in the first chamber are different from the pressure difference that tends to cause mechanical deformation, and the mechanical deformation can damage the unsealed and restricted environment. Wall, - when the expected low pressure 値p〇 in the interior of the unsealed, restricted environment, stop the pumping - by independently adjusting the pressure in each of the chambers Simultaneously introducing a gas into the first chamber and introducing the second chamber, such that the difference between the internal space force of the unsealed, restricted environment and the pressure in the first chamber is a pressure difference that can be mechanically deformed at any time. In a smaller manner, the machine damages the wall of the unsealed, restricted environment, when the atmospheric pressure is obtained, by the unsealed, restricted environment of the contamination prevention enclosure. According to the first embodiment, once the expected low pressure 値P0, the unsealed, restricted environment is at a low pressure to achieve a rise in pressure. The rest may be a few minutes during the period of low pressure, and preferably minutes, in order to obtain complete contamination prevention. This period can be much shorter, or even equal to zero, if it is expected to perform a purge operation. According to the second embodiment, once the expected low pressure 値P0, the rise in pressure starts immediately. The difference between the loops of the system is small. The pressure of the loop is increased, and the pressure in the middle is enough to facilitate the deformation. It is easy to take out before being obtained. At least 1 5 rows are obtained.

-11 - 201226065 [Embodiment] The reticle 1 is shown in Fig. 1 as shown. The pattern is, for example, reproduced on the substrate 2 by a laser beam or an electron beam. The substrate is made, for example, of quartz 3 aligned with the chrome layer 4, and the patterns are etched on the chrome layer 4. For example, the substrate is a 152 mm by a 52 mm square workpiece, 6.35 mm thick. Once etched, the reticle 1 is immersed in a cleaning' to eliminate by-products of the corrosion reaction. If desired, the reticle 1 obtained is then subjected to several successive operations of cleaning, control and repair. The substrate 2 is surrounded by a frame 5 of about 2-6 mm thickness. The frame 5 is made of, for example, a metal frame, such as anodized aluminum. After the final cleaning, the protective film 7 is applied to the substrate 2 and to the upper surface 8 of the frame 5 to separate the internal space 9 contained between the substrate 2 and the film 7 from the external environment. The goal is to protect the effective surface of the reticle 1 from any particular contamination while being positioned outside of the focal zone. The frame 5 can have a number of different geometries (rectangular, curved, octagonal, etc.). The lateral side 10 of the frame 5 has holes 6, which are provided with a diameter of about i mm, and are capable of being in the film. The pressure below the same level as the external pressure is maintained below. These holes 6 have a low conductivity filter that achieves this natural leakage function. The number of these holes 6 is, for example, one to four. This natural leakage must have low conductivity to protect the internal atmosphere of the interior 9 by the effective surface of the reticle 1 and the film 7. It can thus be appreciated that the excessive pumping of the seal to prevent contamination of the enclosure results in a very rapid reduction in the risk of gas pressure surrounding the reticle 1. The gas contained in -12-201226065 of the internal space 9 does not have a time to escape by the holes 6. The internal atmosphere of the interior 9 is then subjected to a pressure higher than the external atmosphere in the enclosure, causing the membrane 7 to experience a differential pressure in the direction from the interior to the exterior. The risk that excessive differential pressure can also manifest is also present during the steps used to raise the pressure. The gas introduced into the enclosure then rapidly raises the gas pressure, which in turn penetrates the natural leak point 6 of the reticle 1 more slowly. The differential pressure then appears in the direction from the exterior to the interior. Excessive differential pressure exerts a mechanical stress that can damage the film 7. In the embodiment of the invention illustrated in Figure 2, an unsealed, restricted environment has been illustrated. In this case, it is attached to the reticle 1 which prevents contamination of the encapsulation member 11. The pollution prevention enclosure 11 has two contamination prevention chambers 12 and 13 separated by a sealing wall surface 14 that withstands the pressure difference. The first sealing chamber 12 occupies a portion of the sealing member that is in contact with the film 7 of the reticle 1. There is no communication between the chamber 12 and the holes 6 to completely limit the environment above the film. The second sealed chamber 13 occupies a portion of the sealing member 11 that is coupled to the hole 6 of the reticle 1, so as to surround the environment outside the chamber 12. Each of the chambers 12, 13 can then be evacuated (arrow 15) or gas filled (arrow 16) independently of each other. Therefore, the pressure P1 in the first chamber 12 may be different from the pressure P2 which is popular in the second chamber 13. The pressure P1 in the first chamber 12 is continuously adjusted to the pressure P3 which is popular in the internal space 9 below the film 7, and as a result, the pressure difference suffered by the film 7 is kept low, preferably Less than 1 Pa. Therefore, the drop in 'pressure' in the second chamber 13 can be fast'

-13- 201226065 The contaminated gas is taken out from the internal space 9 through the low-conductivity filters 6 (arrow 17). The important performance of the leak-tight seal between the two chambers 12 and 13 is known. Above the hole in which the filter 6 is provided, the sealing of the separating wall 14 on the reticle 1 can be obtained on the upper surface 8 of the frame 5 or on the lateral side 10. In the present case, the sealing system of the split wall 14 on the reticle 1 is obtained, for example, by the seal 18 on the side 10 of the frame 5. The chambers 12, 13 preferably have metal walls that independently provide a large degree of freedom in the high pressure impedance of the first chamber 12 and the P2 in the second chamber. . Referring now to Figure 3, there is illustrated an advantageous embodiment of a device comprising a contamination preventing enclosure 13 in accordance with the present invention. The first sealing chamber 31 having the internal volume VI occupies the portion of the sealing member 30 that is in contact with the film 7 of the reticle 1, and is unique to the first mechanism 32 for pumping and for introducing the gas. The first institution 33 cooperates. The pumping mechanism 32 capable of pumping gas away from the first chamber 31 includes a pumping unit 34' connected to the first chamber 31 by a conduit including a variable flow valve 35. The inlet gas mechanism 33 capable of introducing a gas stream into the first chamber 31 is connected to the first chamber 31 by a conduit 36, which includes a flow controller 37, such as a mass flow meter or a variable flow valve. The first chamber 31 is also equipped with a pressure gauge 38. A mechanism (not shown) for controlling the difference between the pressure P3 in the internal space 9 below the film 7 of the reticle 1 and the pressure P1 in the first chamber 31 is used to operate according to the steps of the method. Valve 35 or the flow controller 37. Preferably, the two windows 39a and 39b which are transparent to light are inserted into the wall surface of the film 7 of the first chamber 31 facing the reticle 1. The first chamber 31 may additionally include a mechanism 40 for measuring the deformation of the film 7. The second sealing chamber 41 having the internal volume V2 occupies the second mechanism 42 for the pumping of the sealing member in contact with the hole 6 of the frame 5 of the reticle 1 and for the second mechanism 42 for introducing the gas 43 part of the cooperation. The pumping mechanism 42 capable of pumping gas away from the chamber 41 includes a pumping unit 44 connected to the second chamber 41 by a conduit containing a variable flow valve 45. An introduction gas mechanism 43 capable of introducing a gas flow into the chamber 41 is connected to the chamber 41 by a conduit 46, which includes a flow controller 47 such as a mass flow meter or a variable flow valve. The second chamber 4 1 is also equipped with a pressure gauge 48. The chamber 41 is separated from the first chamber 31 by a sealing wall surface 49. Inside the chamber 41, the reticle 1 is maintained by a positioning mechanism 50, including, for example, an actuator. These positioning mechanisms 50 are particularly used to adjust the height of the reticle 1 to provide an effective seal between the frame 5 of the reticle 1 and the separate wall faces 49 that are contacted by the sleeving members 51. The apparatus for preventing contamination just described has been used to carry out the method of preventing contamination as illustrated by Fig. 4. In order to prevent contamination of the reticle 1, its positioning relative to the dividing wall 49 is adjusted by the positioning mechanism 50 to provide a complete seal between the two chambers 3 1 and 41. The gas is then pumped into the chambers 31 and 41 (curve 60) by means of mechanisms 32 and 42 for pumping, respectively (step A). The mechanisms 32 and 42 for pumping have variable pumping capabilities. -15- 201226065 The pressure in each chamber 31, 41 is regulated by a variable conductance valve 35, 45 placed in the inlet flow, the conductance valve having an adjustable opening. The opening of the valves 35, 45 to a greater or lesser range can be pumped into each of the chambers 31, 41 in a completely separate manner at a higher or lower rate. The gas system present in the interior space 9 is thus removed by means of a hole 6 provided with a low-conductivity filter without removing the film. A mechanism for activation (not shown) is provided to modify the pumping capability of each of the pump units 32 and 42. These mechanisms for starting are driven by a mechanism for controlling the difference between the pressure P3 in the internal space 9 below the film 7 of the reticle 1 and the pressure P1 in the first chamber 31. The mechanism for controlling the pressure difference between the inner space 9 and the first chamber 31 is preferably a mechanism 40 for measuring the deformation of the film 7, which represents the pressure in the inner volume VI of the first chamber 31. The pressure difference ΔΡ between P1 and the pressure P3 in the volume V3 of the internal space 9 is in communication with the internal volume V2 of the second chamber 41, and the pressure P2 is popularized in the internal volume V2. The drive is made such that the measurement of the pressure difference AP 値 P3-P1 is less than the threshold 该 of the pressure difference at any time, and the lanthanum will have the risk of damaging the mechanical deformation of the film 7. The gas system is taken out from the inner space 9 through a hole 6 having a low-conductivity filter which is formed in the frame 5 of the film 7 supporting the reticle 1 without removing the film 7. Due to the conduction of the holes 6, the pressure P3 in the internal space 9 is larger than the pressure P2 in the second chamber 41. When pumping into the second chamber 41, it is possible to take this pressure difference into account and thus adjust the pressure P1 such that it is always slightly smaller than the pressure P1 in the first chamber 31. Therefore, -16-201226065, the pressure P3 in the internal space 9 can be maintained at the same level as the pressure P1 in the first chamber 31 at any time. Therefore, the mechanical deformation of the film 7 is kept low enough without causing any damage. With the conventional conductivity of the filters 6, it is possible to produce a correct calculation of the pressure difference P3-P2 caused by it, in order to adjust the pumping capacity of the pumping mechanism 42 of the second chamber 41, such as A function of the pressure P1 in the first chamber 31. The mechanism 40 for measuring deformation, which can be seen in Figure 3, can be used to control the deformation of the film 7 via the use of a laser 52 and a light receiver 53, the light receiver comprising a group of light receivers Unit 1. The laser 52 emits a linear beam 54 of a width of a few millimeters and is directed to the film 7 (preferably toward its center) at a degree of angle relative to a direction perpendicular to the surface of the film 7. The incident beam 54 passes over the window 39a and becomes reflected on the surface of the film 7. The reflected beam 55 passes over the window 39b and reaches the light receiver 53. Since the laser 52 and the light receiver 53 are in a fixed position, the deformation of the film 7 directly causes displacement of the reflected beam 5 5 received by the light receiver 53. Therefore, it is possible to use a mechanism 40 for measuring the deformation of the film to determine that the pressure P3 in the internal space 9 has a small difference from the pressure P 1 in the first chamber 31. The mechanism 40 for measuring the deformation of the film 7 can be used to adjust the pumping rate in any of the chambers 31 and 41 as a function of the observed deformation of the film 7. Once the pressure P3 has been obtained in the internal space 9, and at a level equal to the set sufficiently low pressure P0, it is possible to separately set a rest time (step B) in order to achieve the desorption of such contaminant species. (曲-17- 201226065 line 6 1). In order to obtain a significant result from the viewpoint of preventing contamination, it is preferred that the rest time should be at least 15 minutes. Naturally, if the contamination is extremely small, it may be preferable to perform a single purification operation which requires a short rest period, or even a total endless time. In the latter case, the rise in pressure can occur immediately after the pumping is stopped (curve 62). Alternatively, after a period of inactivity, it may be enhanced to atmospheric pressure Patm (curve 63) in the enclosure 30 by simultaneously injecting a mixture of gases or gases into the chambers 31 and 41 (step C). The gas is introduced into the internal space 9 by a hole 6 provided with a low-conductivity filter without removing the film. A mechanism (not shown) for starting up such as a flow controller is designed to independently modify the flow rate of the injection gas by each of the introduction mechanisms 33 and 43. The large or small amount of this injection flow can cause atmospheric pressure to rise faster or slower. These mechanisms for starting are driven by a mechanism (not shown) for controlling the difference between the pressure in the internal space 9 under the film 7 of the reticle 1 and the pressure in the first chamber 31. A mechanism for controlling the difference between the pressure in the internal space 9 and the pressure in the first chamber 31 is preferably a mechanism 40 for measuring the deformation of the film 7, such as the first chamber 31 and The function of the pressure difference ΔΡ between the internal spaces 9 in which the second chamber 41 communicates. The gas system is introduced from the internal space 9 through a hole 6 having a low-conductivity filter which is formed in the frame 5 of the film 7 supporting the reticle 1 without removing the film 7. Once the atmospheric pressure has been restored in the chambers 31 and 41 and in the interior space 9, the reticle can be set spaced from the positioning mechanism 50.

S -18- 201226065 ' and finally removed by the pollution prevention enclosure. Naturally, the present invention is not limited to the embodiments described, but can be deviated from the spirit of the invention for those objects of many alternative embodiments that are well understood by those skilled in the art. In particular, it may not modify the shape and volume of the pollution prevention chambers separately from the structure of the present invention, and any conventional mechanism may be used to control and/or compare the pollution prevention chambers and the unsealed, restricted The pressure in the internal space of the environment. BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the present invention will be apparent from the following description of the preferred embodiments and the reading of the accompanying drawings. This embodiment is of course given as non-exhaustive description: - Figure 1 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 2 is a cross-sectional view of a reticle in a contamination preventing encapsulation according to an embodiment of the present invention; FIG. 3 is a view for preventing contamination according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The device is intended to be used to prevent contamination of a reticle having a film; - Figure 4 is a summary of the progress of the pressure in the internal space below the film during the sequencing of the different steps of the method. The pressure P3 in the interior space of the unsealed, restricted environment is indicated on the y-axis and the progression of the method during this time τ is indicated on the X-axis. In the drawings, the identical components have the same reference numerals. 201226065 [Description of main components] 1 : Photomask 2 : Substrate 3 : Quartz 4 : Chromium layer 5 : Frame 6 : Hole 7 : Film 8 : Upper surface 9 : Internal space 1 〇 : Horizontal side 1 1 : Enclosure 1 2 : Pollution prevention chamber 1 3 : Pollution prevention chamber 1 4 : Seal wall surface 1 5 : Arrow 16 : Arrow 1 7 : Arrow 1 8 : Seal 3 0 : Enclosure 3 1 : Seal chamber 3 2 : Mechanism for pumping 3 3 : First mechanism 34: pump unit

S -20- 201226065 3 5 : Variable flow valve 36 : conduit 3 7 : flow controller 3 8 : pressure gauge 39a : window 39b : window 40 : mechanism 4 1 : sealed chamber 42 : mechanism for pumping 43 : Mechanism for introducing gas 44: Pump unit 45: Variable flow valve 46: Catheter 4 7: Flow controller 4 8: Pressure gauge 49: Sealing wall 5 〇: Positioning mechanism 5 1 : Seal 5 2: Laser 5 3 : Light Receiver 54: Beam 5 5 : Reflected Beam 60: Curve 6 1 : Curve-21 - 201226065 62 : Curve 63: Curve

S -22-

Claims (1)

201226065 VII. Scope of application for patents: 1. A device for preventing contamination of an unsealed, restricted environment (1) that has a natural leak (6) and contains an internal space bounded by a wall (7) ( 9) The apparatus comprises: - a pollution prevention enclosure (1 1, 30) capable of containing the unsealed, restricted environment (1), - a mechanism (3 2, 42) for pumping gas out of the a pollution prevention sealing member (11), a mechanism (3 3, 43) for introducing a gas into the pollution prevention sealing member (11), characterized in that the pollution prevention sealing member (11, 30) has a seal and a separation At least two chambers (12, 13; 31, 41) separated by walls (14, 49), the wall being able to withstand the difference in pressure between the two chambers (12, 13; 31, 41): - first The chamber (12, 31) is located in contact with the wall (7) of the unsealed, restricted environment (1), and with the first mechanism (32) for pumping gas and for introducing gas. The first body (33) cooperates with the part, - the second chamber (13, 41) is located and unsealed by the seal The natural environment (1) of the restricted environment (1) is in contact with, and is combined with a second mechanism (42) for pumping gas and a second mechanism (43) for introducing gas, for the pump The first and second mechanisms (32) and (42) of the gas having independently capable pumping capability, and the first and the -23-201226065 second mechanisms (33) and (43) for introducing the gas ) having a gas injection flow rate that can be varied independently, and wherein the means for preventing contamination includes controlling the pressure P3 in the internal space (9) of the unsealed, restricted environment (1) and the first chamber The mechanism of the difference between the pressures P1 in (12, 31). 2. The device of claim 1, wherein the first chamber (12, 31) has a smaller volume VI than the volume V2 of the second chamber (13, 41). 3. The device of any one of claims 1 and 2, wherein the first chamber (12, 31) has a window (39a, 39b) that is transparent to light. ο 4 as claimed in claim 3 The device comprises a mechanism (40) for measuring the deformation of the wall (7) of the unsealed, restricted environment (1). 5. The device of claim 4, wherein the mechanism (40) for measuring deformation of the wall (7) comprises directing a beam of light toward a wall (7) of the unsealed, restricted environment (1) A laser (52)' and a light receiver (53) that receives a beam of light reflected by the wall (7) of the unsealed, restricted environment (1). 6. The device of claim 4, wherein the pressure P3 in the internal space (9) of the unsealed, restricted environment (1) and the first chamber (12) The mechanism for the difference between the pressures P1 in , 31) is a mechanism for measuring the deformation of the wall surface of the unsealed, restricted environment. 7. If the device of claim 1 or 2 is applied, the mechanism for the activation of the 24-200 201265 is also included to independently modify each of these rooms (1 2,1 3 ; 3 1 , 4 1 ) The pumping rate in one. 8. If the device of claim 1 or 2 is applied for, further includes a mechanism for activation to independently modify the flow rate of the gas injected into each of the chambers (12, 13; 31, 41). . 9. The apparatus of claim 1 or 2, further comprising a mechanism (50) for positioning the unsealed, restricted environment (1) within the pollution prevention enclosure (11, 30). 10. A method for preventing contamination of an unsealed restricted environment (1) by means of a device as claimed in claim 1 or 2, the environment having a natural leak (6) and including by a wall (7) a defined internal space (9), the method comprising the steps of: - placing the unsealed, restricted environment (1) in a pollution prevention enclosure (1 1,300), the enclosure comprising by sealing Separate the two compartments separated by the wall (1 4, 4 9 ) (1 2, 1 3 ; 3 1, 4 1 ), - set up the separate wall on the unsealed, restricted environment (1) (14, 49 Sealing - by independently adjusting the pressure drop in each of the chambers (12, 13; 31, 41) while pumping out the gas contained in the first chamber (12, 31) a gas contained in the second chamber (31, 41), and thereby a pressure P3 in the internal space (9) of the unsealed, restricted environment (1) and the first chamber (12, The difference between the pressures P1 in 31) is in a manner that is less than the pressure difference that tends to cause mechanical deformation at any time, and the mechanical deformation can damage the unsealed, restricted Wall (7) of the environment (1) -25- 201226065 - When the pressure P3 in the internal space (9) of the unsealed, restricted environment (1) obtains the expected low pressure 値p〇, stop the pump Out, - by independently adjusting the rise in pressure in each of the chambers (! 2, 13; 31, 41) while introducing gas into the first chamber (12, 31) and into the second chamber (13, 41), and thereby making the difference between the pressure in the internal space (9) of the unsealed, restricted environment (1) and the pressure in the first chamber (12, 31) Δρ a wall surface (7) that is less susceptible to the difference in pressure that can cause mechanical deformation, and which is susceptible to damage to the wall (7) of the unsealed, restricted environment (1), when the atmospheric pressure Patm is obtained, is sealed by the pollution prevention The piece (1 1 , 3 0 ) takes out the unsealed, restricted environment (1). 11. A method of preventing pollution according to claim 10, wherein the unsealed, restricted environment (1) is allowed to rest before the pressure rise is achieved once the expected low pressure 値P0 is obtained. Low pressure 〇 12. The method of preventing pollution according to claim 11 of the patent application, wherein the rest is at least 15 minutes during the period of low pressure. 3 -26-